Lubricant compositions such as spin finishes, coning oils, etc. are conventionally applied to textile yarns at various stages during the manufacturing operation to facilitate handling and processing the yarns on textile machinery. It is generally recognized that these lubricants must be applied at carefully controlled levels, since application of improper amounts of lubricant results in various production and quality problems as the yarns are processed into fabrics. For example, when producing knitted fabrics, the application of excessive amounts of lubricant to the knitting yarns may result in a build-up and eventual gumming of the needle latches of the knitting machine, while application of too little lubricant results in excessive needle wear and broken filaments or ends.
Also, it is recognized that it is quite important to apply the lubricant at a uniform level to all of the ends being processed at the respective positions on the textile machinery. Otherwise, when several ends are woven or knitted into a fabric, the variations in lubricant level on the respective ends may become apparent in the fabric as streaking, barre, or uneven dyeing. For example, different levels of lubricant on the several ends fed to a knitting machine may result in variations in tension in the respective yarns which would be readily apparent in the knitted fabric.
Therefore, it is conventional procedure to periodically test the level or percent of lubricant applied to each end being processed to insure that the proper level of lubricant is being applied. This determination of the percent lubricating oil on a yarn has conventionally been made by laboratory extraction methods. In this laboratory procedure, a predetermined length of yarn is taken from a previously wound yarn package, weighed, and placed in a container for a length of time with a heated solvent for the lubricant. After the lubricant has been extracted from the yarn by dissolving in the solvent, the yarn is removed from the container and dried, and the yarn is again weighed to determine the weight percent of oil which was present on the yarn. Obviously this is a time-consuming procedure which takes several hours and requires the dual work of both laboratory technicians and plant personnel. The procedure requires several weighings and measurements and thus provides considerable opportunity for human error. In the several hours of elapsed time between when the sample is taken and when the results are obtained, several thousand dollars worth of yarn containing either too much or too little lubricant may have been produced.
Several proposals have been made for reducing the amount of time required for determining the level of lubricant oil on a yarn. For example, Finucane U.S. Pat. No. 3,459,506 discloses a method wherein the amount of lubricant on the yarn is determined by titration. Another proposed testing procedure disclosed in Textile World, July 1974, page 12, employs infrared spectroscopy to obtain a measurement of the amount of oil on the yarn. However, both of these proposed methods still require that a sample of yarn be removed from a previously wound yarn package and subjected to laboratory analysis to determine the amount of lubricant on the yarn. Thus, there is still a significant amount of elapsed time between when the sample is taken and when the results are available, and further, the numerous handling and measuring operations still provide a significant chance for the introduction of human error.
With the foregoing in mind, it is a primary object of this invention to provide a method for determining the amount of a coating composition applied to a strand much more rapidly than has been possible heretofore.
It is another object of this invention to provide a testing method which not only significantly reduces the amount of time required to determine the amount of the coating composition on a strand, but which also provides more reproducible and accurate results than is presently possible by conventional laboratory techniques.
It is a further object of this invention to provide a testing method for determining the amount of lubricant on a textile yarn which may be performed by one individual, and which may be performed in the plant, if desired, rather than in a laboratory.
It is a still further object of this invention to provide a testing method for determining the amount of lubricant coating applied to a textile yarn wherein it is not necessary to remove a length of yarn from a package to obtain a sample but wherein a nondestructive measurement may be made directly to the yarn package, and wherein the measurement may be made in the plant either while the yarn is still being wound into a package or after completion of winding and doffing of the package, and wherein the results of the measurement are available almost immediately so that corrective measures may be taken if an improper amount of lubricant is being applied.